An embodiment of the invention relates to a thin film transistor liquid crystal display (TFT-LCD) array substrate, a method and an apparatus for detecting size or alignment deviation of multilayer patterns.
TFT-LCDs have been dominating the flat panel display market due to their advantages such as small volume, low power consumption and being free of radiation. A TFT-LCD is formed by assembling together an array substrate and a color filter substrate. On the array substrate, gate lines and data lines, which intersect with each other, are provided so as to define pixels, and a pixel electrode and a thin film transistor are provided in each pixel. By applying driving signals on gate lines, image data are applied to pixel electrodes in pixels via data lines. Orientation of liquid crystal molecules between the array substrate and the color filter substrate is controlled by voltage applied through the pixel electrodes so as to control the resultant intensity of the light passing therethrough, and then with the color filter substrate, an image can be presented on the panel of the TFT-LCD.
Currently, during the manufacturing process of a TFT-LCD, the sizes of the multilayer patterns formed on the TFT-LCD array substrate need to be detected so as to assure the uniformity of the process parameters and the stability of the product properties. The detecting may be conducted as follows. A microscope is moved to a certain area to be detected and a shot is taken with respect to the specified patterns in the area, and then the line width of the targeted pattern in the taken picture is obtained by using an image processing program. Generally speaking, the detecting process comprises the following steps: moving a glass substrate (the array substrate) to a detecting base station, aligning the glass substrate, positioning the detecting coordinate system, taking a picture of a certain area, conducting grey identification and measurement on the line width, and the like. With the above steps, the sizes of the patterns on the array substrate can be measured.
It is noted that the conventional detecting method for the TFT-LCD array substrate is time-consuming, and about 20 minutes to 30 minutes are taken to detect one array substrate due to the fussy detecting steps. Therefore, this results in lengthening of the whole production time and disadvantageously influences the production efficiency in the mass production.